Are they breaking the same place every time? Like where grease fitting goes.
I find it difficult to imagine that pin breaking, it should withstand anything you can do to it and then some. Unless its from backing into something while driving tractor.
Had a trailer that was snapping axles, they were bolt in stubs. Every time they sheared at grease fitting. Had a machinist crank out four new ones,without grease hole and never broke one since.cheaper than factory replacements i might add.
Perhaps pin material is too hard. But too soft and they bend, then impossible to remove.
It may help to know what type of work you are dong with tractor, perhaps other bh77 owners may chime in.